Method and system for data communication in human body and sensor therefor

ABSTRACT

The present invention provides method and system for data communication in the human body and a sensor therefor. The method and system transmit information through the human body to a receiver located outside the human body using low current and voltage polarity, so that they cause no damage to the human body and achieve low power consumption and better receiving sensitivity. In addition, the sensor contains a CMOS image sensor on which all circuits are integrated without radio transmitter and antenna, so that it achieves a low-priced and small-sized capsule type endoscope.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a 35 U.S.C. §371 national phase conversion ofPCT/KR2003/002937 filed 31 Dec. 2003, which claims priority of KoreanPatent Application No. 10-2003-0005059 filed 25 Jan. 2003.

TECHNICAL FIELD

The present invention relates to a method and system for transmittingdata from a sensor put in the human body to the outside of the humanbody to collect various medical information, and particularly to amethod and system for data communication in human body, wherein acurrent generated from the sensor flows through the human body as aconductor to transmit data to the outside of the human body.

BACKGROUND ART

Various sensors for collecting medical information in the human bodyhave been developed and used, herein, not only a technique forcollecting information in the human body but also a technique fortransmitting collected information to the outside of the human body arevery important.

In general data transmitting methods, there is a communication cablemethod applied to an endoscope which is developed for observing thestomach and intestines. In the communication cable method, a cable madeof a conducting wire or an optic fiber is inserted into the human bodythrough throat of the patient. The communication cable method has highreliability and high data quality, however, it may cause severe pain tothe patient.

In order to solve the above-mentioned problem, Given Imaging LTD. inIsrael has developed a capsule type endoscope called M2A. When a patientswallows the capsule type endoscope like a tablet, video data in thehuman body photographed by a camera of the endoscope are transmitted toan external-receiving unit, and displayed in a monitor.

However, in the capsule type endoscope, since radio wave is used totransmit a signal, power consumption is large, so that operation time isshort, and receiving sensitivity is deteriorated due to interference ofvarious electric waves from the outside of the human body. In addition,radio-transmitting apparatus such as a converter circuit for convertinga video signal into a high frequency signal and an antenna for signaltransmission, etc. are required, so that volume is increased andproduction cost is increased. Also, high frequency may be harmful to thehuman body.

SUMMARY OF THE INVENTION

In order to solve the above-described problems, it is an object of thepresent invention to provide a method and system for data communicationin the human for flowing a current generated from the sensor through thehuman body to transmit data to the outside of the human body.

In addition, it is another object of the present invention to provide asensor having a transmitting electrode capable of generating a currentin the human body to flow a current through the human body to transmitdata to the outside of the human body.

In order to achieve the above-mentioned objects, in a method fortransmitting a signal from a sensor put in the human body to the outsideof the human body, a method for data communication in the human body inaccordance with the present invention includes the steps of generatingelectric potential difference between transmitting electrodes installedon the surface of the sensor; supplying a current from the transmittingelectrode having higher electric potential to the inside of the humanbody to flow the current through the surface of the human body back intothe inside of the human body and sinking the current to the transmittingelectrode having lower electric potential; and inducing a voltagebetween receiving electrodes installed on the surface of the human bodyby the current flowing through the surface of the human body.

In addition, a system for data communication in the human body inaccordance with the present invention includes a sensor, which is put inthe human body, having transmitting electrodes for generating electricpotential difference; and a receiver installed on the surface of thehuman body for receiving a current generated by the electric potentialdifference through the human body.

In addition, a sensor in accordance with the present invention includesa lighting device for irradiating the inside of the human body; a lensfor focusing light incident from the inside of the human body; a CMOSimage sensor for generating an electric signal from the light focused bythe lens; a housing for containing the lighting device, the lens and theCMOS image sensor; and a transmitting electrode installed on the surfaceof the housing to receive the electric signal.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is an exemplary view illustrating a method for data communicationin the human body in accordance with the present invention;

FIG. 2 are perspective views illustrating several embodiments of atransmitting electrode installed to the surface of a sensor used in asystem for data communication in the human body in accordance with thepresent invention;

FIG. 3 is a sectional view illustrating the sensor of the system fordata communication in the human body in accordance with the presentinvention; and

FIG. 4 is a circuit diagram illustrating an internal construction of aCMOS image sensor of the sensor.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the preferred embodiment of the present invention will bedescribed with reference to accompanying drawings.

FIG. 1 is an exemplary view illustrating a method and a system for datacommunication in the human body in accordance with the presentinvention. As depicted in FIG. 1, a sensor 10 placed inside the humanbody 1, for example, in the digestive organs transmits information ofthe inside of the human body 1 to a receiver 20 installed on the surfaceof the human body through the human body 2.

With reference to FIG. 1, in the system for data communication in thehuman body in accordance with the present invention, a method for datacommunication in the human body capable of transmitting a signal fromthe sensor 10 inside the human body 1 to the receiver 20 placed in theoutside of the human body will be described in more detail. Variousinformation (for example, pictures of the inside of the body, PH,temperature or electric impedance, etc.) collected by the sensor 10 isconverted into an electric signal by a signal processing circuit of thesensor and is applied to a transmitting electrode 11 through an outputline of the signal processing circuit, and accordingly electricpotential difference occurs between the two transmitting electrodes 11.Because the transmitting electrode 11 is contacted to the inside of thehuman body 1 (it is electrically connected with the human body throughbody fluids in the digestive organs), by electric potential differencebetween the two transmitting electrodes 11, a current 3 flows throughthe human body 2. The current 3 flows from the transmitting electrodehaving higher electric potential through the surface of the human bodyback into the inside of the human body 1 and is sunken to thetransmitting electrode having lower electric potential. Herein, thecurrent flowing through the surface of the human body induces a voltagebetween two receiving electrodes 21, a signal transmitted from thesensor 10 put in the human body 1 can be sensed by the receiver 20outside of the human body. The receiver 20 restores a video signal byprocessing the received signal, displays it on a monitor or stores it ina memory.

FIG. 2 illustrate several embodiments of the transmitting electrode 11installed on the surface of the sensor 10 of the system for datacommunication in the human body in accordance with the presentinvention. On the surface of the sensor 10, two metal plates, namely,two transmitting electrodes are formed, which are respectively connectedto outlines of a signal processing circuit of the sensor.

If the two transmitting electrodes are electrically isolated andseparated from each other sufficiently, the transmitting electrodes canbe formed at any position of the surface of the sensor. Herein, it ispreferable that the transmitting electrodes have a sensor-coveringshape, namely, a three-dimensionally curved shape in order to becontacted with the inside of the human body easily.

In FIG. 2, (a) shows a structure of the transmitting electrode of sensorshown in FIG. 1. The transmitting electrode consists of a firstelectrode and a second electrode respectively surrounding the both endsof the sensor. A transmitting electrode shown in (b) consists of a firstelectrode surrounding an end of the sensor and a second electrodecovering the other end of the sensor as a band shape. A transmittingelectrode shown in (c) consists of a first electrode and a secondelectrode respectively covering both ends of the sensor as a band shape.In addition, a transmitting electrode shown in (d) consists of a firstelectrode and a second electrode symmetrically formed along a longeraxis of the sensor.

Because the transmitting electrode is exposed to the inside of the humanbody, it has to be made of metal having good resistance againstcorrosion by a reactive material such as a digestive fluid, etc. andalso harmless to the human body. In the embodiments of the presentinvention, as metal having good corrosion resistance and harmless to thehuman body, SUS316L or gold is used. In addition, in order to isolatethe transmitting electrodes formed on the surface of the sensorelectrically, the surface of the sensor has to be a nonconductorharmless to the human body. As a nonconductor harmless to the humanbody, peek, polyethylene or polypropylene in a plastic group may beused. In order to improve harmlessness to the human body, parylene maybe coated onto the surface of the sensor made of peek, polyethylene orpolypropylene.

FIG. 3 is a sectional view illustrating an internal structure of acapsule type endoscope as a sensor used for the system in accordancewith the present invention. As depicted in FIG. 3, the capsule typeendoscope has a diameter of 10 mm and a length of 20 mm. A lightreceiving window 17 of dome shape is formed in an end of a housingforming an external shape of the capsule type endoscope, and arectangular container 18 is formed in the other end of the housing.Accordingly, the capsule type endoscope has a bullet shape.

In the capsule type endoscope, the light receiving window 17 which is apart for passing light is made of a nonconductor harmless to the humanbody and passing light. The container 18 that is a part for containingseveral devices also is made of a nonconductor harmless to the humanbody. The light receiving window 17 and the container 18 are sealed sothat infiltration of a digestive fluid, etc. into the capsule typeendoscope may be prevented and also leakage of substances in the capsuletype endoscope into the human body may be avoided.

As depicted in FIG. 3, the capsule type endoscope has the external shapeof the housing consisting of the light receiving window 17 and thecontainer 18. The container 18 includes a lighting device 12, a lens 13,a CMOS image sensor 14 and a battery 15 and a transmitting electrode 11electrically isolated-formed on the surface of the container 18.

First, the lens 13 is arranged behind the light receiving window 17, andthe CMOS image sensor 14 in which various circuits are integrated isarranged behind the lens 13. A distance between the lens 13 and the CMOSimage sensor 14 is adjusted so as to focus light incident through thelight receiving window 17 on the surface of the CMOS image sensor 14.Around the lens 13 and the CMOS image sensor 14, plural lighting devices12 are arranged as donut-shape. In the embodiment of the presentinvention, four LEDs are used for the lighting devices 12.Non-reflection coating is performed on the inner and outer surfaces ofthe light receiving window 17 so that light irradiated from the lightingdevice 12 may pass through the light receiving window 17 smoothly andilluminate an object. A battery 15 as power supply is arranged behindthe CMOS image sensor 14. In the embodiment of the present invention, asilver oxide battery having an even discharge voltage and causing littleharm to the human body is used as the battery 15.

The operation of the capsule type endoscope will be described. While thelighting devices 12 irradiate a light, the CMOS image sensor 14 capturesan image of the object through the lens 13. The CMOS image sensor 14processes the captured video signal through various internal circuitsand applies the signal to the transmitting electrodes respectivelyconnected to the two output lines 16, and accordingly the receivingelectrode placed in the outside of the human body can sense the signal,as described above.

FIG. 4 is a circuit diagram illustrating the CMOS image sensor 14 inorder to describe the operation principles of the capsule type endoscopein more detail.

As depicted in FIG. 4, the CMOS image sensor 14 includes a pixel array100 for capturing and storing a video signal; a read circuit 110 forfetching a signal of each pixel sequentially; a coding circuit 120 forcoding an output signal of the read circuit 110; a switching circuit 130for transmitting a signal coded in the coding circuit 120 through thetwo output lines; a current limiting circuit 140 for adjusting a currentvalue so as to prevent flowing of a current causing damage to the humanbody; a control circuit 150 for controlling the signal processing andthe operation of the lighting device 12; and an oscillating circuit 160for determining an operational frequency.

In the embodiment of the present invention, the pixel array 100 (of320×240 pixels) can capture and store video signals of high resolution.The read circuit 110 processes the stored video signals sequentially asa frame or more per 1 sec, and accordingly there is no need to have amemory disadvantageous in the cost and volume aspects. In addition, thecontrol circuit 150 determines brightness inside the human body based onbrightness of light incident to the pixel array 100 and controls thelighting device 12 to operate variably for 5˜200 msec. The video signalsare captured by the pixel array 100 during that time. According to that,each video frame is instantly captured, and brightness thereof isbetter. And a PSK method that is simple and has strong tolerance againstnoise is used in encoding.

When the signal transmitted from the coding circuit 120 is “1”, theswitching circuit 130 applies+voltage to the first output line 16 a andgrounds the second output line 16 b. When the signal transmitted fromthe coding circuit 120 is “0”, the switching circuit 130 grounds thefirst output line 16 a and applies a+voltage to the second output line16 b. As described-above, since the present invention transmits a signalusing not the voltage size but the voltage polarity, it can be strongerto noise.

The current limiting circuit 140 serves to prevent a current more than 5mA from flowing through the human body. In the embodiment of the presentinvention, the current limiting circuit 140 is implemented by seriallyconnecting resistors to the two output lines 16 of the switching circuit130 respectively. For example, assume that when a power voltage is 3 Vthe current limiting circuit 140 comprises resistors of 300 ohmsserially connected to the two output lines respectively. In this case,although the transmitting electrode has a substantial short circuitbecause of very small resistance of the human body, current flowingthrough the human body does not exceed 5 mA. In addition, by connectinga capacitor to each resistance in parallel, it is possible to remove ahigh frequency component of the signal transmitted to the human body andperform electric matching with the human body, so thatsignal-transmitting performance can be improved.

The signal passing the current limiting circuit 140 is applied to thetwo transmitting electrodes 11 and is transmitted to the outside of thehuman body through the human body. In the conventional frequencycommunication method, a high frequency signal of several hundred MHz isrequired, however, in the present invention, a video signal captured bythe capsule type endoscope can be transmitted to the outside of thehuman body with a low frequency signal of 10 MHz.

Industrial Applicability

Since the present invention uses a low frequency and current instead ofa high frequency through antenna when communicating with sensor in thehuman body, it reduces power consumption and attenuation in human body,has no effect on external interference and cause no damage to the humanbody. In addition, since the invention transmits a signal using voltagepolarity, it is strong to noise, and accordingly receiving sensitivityis superior.

In addition, the sensor in accordance with the present invention doesnot need a radio transmitter and antenna, and also does not need anadditional memory because it processes video signals sequentially alongthe passage of time, so that a small-sized and low-priced capsule typeendoscope can be provided.

1. A method for transmitting a signal from a sensor put in a human bodyto the outside of the human body, the method comprising: generatingelectric potential difference between transmitting electrodes installedon the surface of the sensor, the sensor capable of being ingested andcapable of traveling autonomously within the human body; switching thetransmitting electrodes according to information to be transmitted, tocreate: a first state, wherein a first transmitting electrode has ahigher electric potential and a second transmitting electrode has alower electric potential; and a second state, wherein the firsttransmitting electrode has a lower electric potential and the secondtransmitting electrode has a higher electric potential; supplying aconduction current from the first transmitting electrode having thehigher electric potential to an inside of the human body to flow acurrent through a surface of the human body back into the inside of thehuman body, and sinking the current to the second transmitting electrodehaving lower electric potential; inducing a voltage between receivingelectrodes installed on the surface of the human body by the currentflowing through the surface of the human body; and controlling an amountof the conduction current flowing through the body, wherein during thefirst state, a positive voltage is applied to the first transmittingelectrode and the second transmitting electrode is grounded, and whereinduring the second state, the first transmitting electrode is groundedand the positive voltage is applied to the second transmittingelectrode.
 2. The method of claim 1, wherein the generating the electricpotential difference comprises controlling an output of the transmittingelectrodes to be transmitted to an outside of the human body by aswitching circuit.
 3. The method of claim 2, wherein the controlling ofthe output of the transmitting electrodes comprises switching an inputsignal to the transmitting electrodes by the switching circuit, so that:the first state is represented when the first transmitting electrode hasa higher electric potential and the second transmitting electrode has alower electric potential; and the second state is represented when firsttransmitting electrode has a lower electric potential and secondtransmitting electrode has a higher electric potential.
 4. The method ofclaim 3, further comprising supplying the conduction current in adigital form.
 5. The method of claim 4, further comprising inducing adigital voltage between the receiving electrodes installed on thesurface of the human body by the conduction current flowing through thesurface of the human body.
 6. A system for data communication in a humanbody, the system comprising: a sensor, which is put in the human body,and having transmitting electrodes installed on a surface of the sensorconfigured to be electrically isolated and configured to generateelectric potential difference, the sensor capable of being ingested andcapable of traveling autonomously within the human body, a codingcircuit located in the sensor; a switching circuit that switches, basedon an output from the coding circuit, the transmitting electrodes, tocreate: a first state, wherein a first transmitting electrode has ahigher electric potential and a second transmitting electrode has alower electric potential; and a second state, wherein the firsttransmitting electrode has a lower electric potential and the secondtransmitting electrode has a higher electric potential; a receiverinstalled on a surface of the human body to receive a conduction currentgenerated by the electric potential difference through the human body;and a circuit to control an amount of the conduction current flowingthrough the body, wherein during the first state, the switching circuitapplies a positive voltage to the first transmitting electrode andgrounds the second transmitting electrode, and wherein during the secondstate, the switching circuit grounds the first transmitting electrodeand applies the positive voltage to the second transmitting electrode.7. The system of claim 6, wherein the transmitting electrodes areinstalled on the surface of the sensor and are configured to beelectrically isolated.
 8. The system of claim 7, wherein thetransmitting electrodes are three-dimensionally formed.
 9. The system ofclaim 8, wherein the sensor includes a first electrode and a secondelectrode which surround both ends of the sensor.
 10. The system ofclaim 8, wherein the sensor includes a first electrode surrounding anend of the sensor and a second electrode covering an other end of thesensor as a band shape.
 11. The system of claim 8, wherein the sensorincludes a first electrode and a second electrode respectively coveringboth ends of the sensor as a band shape.
 12. The system of claim 8,wherein the sensor includes a first electrode and a second electrodesymmetrically formed along a longer axis of the sensor.
 13. The systemof claim 6, wherein the transmitting electrodes are electricallyconnected with an internal circuit of the sensor to receive an electricsignal generated from the internal circuit.
 14. The system of claim 6,wherein the surface of the sensor for isolating of the transmittingelectrodes is made of one of peek, polyethylene and polypropylene. 15.The system of claim 14, wherein the surface of the sensor for isolatingof the transmitting electrodes is coated with Parylene.
 16. The systemof claim 6, wherein the surface of the sensor is made of a conductivematerial harmless to the human body.
 17. The system of claim 16, whereinthe conductive material comprises SUS316L or gold.
 18. The system ofclaim 6, wherein the sensor further comprises a current limiting circuitthat is located between the switching circuit and the transmittingelectrodes.
 19. A method for transmitting a signal from a capsule typeendoscope put in a human body to an outside of the human body, themethod comprising: generating electric potential difference between afirst transmitting electrode and a second transmitting electrodeinstalled on a surface of a capsule type endoscope, the capsule typeendoscope capable of being ingested and capable of travelingautonomously within the human body; switching the transmittingelectrodes according to information to be transmitted, to create: afirst state, wherein the first transmitting electrode has a higherelectric potential and the second transmitting electrode has a lowerelectric potential; and a second state, wherein the first transmittingelectrode has a lower electric potential and the second transmittingelectrode has a higher electric potential; supplying a conductioncurrent from the first transmitting electrode having a higher electricpotential to an inside of the human body to flow a current through asurface of the human body back into the inside of the human body andsinking the current to the second transmitting electrode having thelower electric potential; inducing a voltage between receivingelectrodes installed on the surface of the human body by the currentflowing through the surface of the human body; and controlling an amountof the conduction current flowing through the body, wherein the capsuletype endoscope makes a current flow from one transmitting electrode tothe other transmitting electrode when a signal to be transmitted is adigital signal “1” and makes a current flow from the other transmittingelectrode to one transmitting electrode when a signal to be transmittedis a digital signal “0.”
 20. The method of claim 19, wherein a size ofthe current is limited by connecting resistance serially to thetransmitting electrode respectively.
 21. The method of claim 20, whereina capacitor is connected to each resistance in parallel.